The present invention relates to sealing improvements in turbomachinery. More specifically, the invention relates to a floating fluid film sealing configuration with an obstruction.
Floating fluid film seals are designed to force a seal fluid, such as oil, into a machine in order to prevent process fluid from escaping from a pressure casing down a shaft. Seal fluid exiting the seal contacts process fluid and becomes contaminated, or “sour.” The sour oil is drained away from the seal for reclamation or disposal. Current seals result in a negative pressure differential at an entrance to the seal, which thereby creates negative flow across the seal resulting in contamination of the seal fluid, or “sweet” oil. Further, seals have an oil flow swirl ratio, which may be defined as a ratio of local angular velocity to shaft angular velocity. Current seals often result in a higher swirl ratio at the entrance to the seal, which creates a pressure drop exceeding the supplied differential pressure. This can cause contamination of the sweet oil with the process gas. Such discrepancies result in a secondary flow within the seal fluid that is directed towards the inner seal, which also results in a greater pressure drop adjacent the seal entrance.